////////////////////////////////////////////////////////////////////////////////
// Filename: lightshaderclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "lightshaderclass.h"

LightShaderClass::LightShaderClass() : 
	m_vertexShader(0), m_pixelShader(0), m_layout(0), m_sampleState(0), m_matrixBuffer(0), 
	m_lightBuffer(0), m_cameraBuffer(0)
{ }

LightShaderClass::LightShaderClass(const LightShaderClass& rhs)
{ }

LightShaderClass::~LightShaderClass()
{ }

bool LightShaderClass::Initialize(ID3D11Device* device, HWND hwnd)
{
	bool result;

	// Initialize the vertex and pixel shaders.
	result = InitializeShader(device, hwnd, L"bulat-research-project/graphics/hlsl/light_vs.hlsl", L"bulat-research-project/graphics/hlsl/light_ps.hlsl");
	if (!result)
	{
		return false;
	}

	return true;
}

void LightShaderClass::Shutdown()
{
	// Shutdown the vertex and pixel shaders as well as the related objects.
	ShutdownShader();

	return;
}

bool LightShaderClass::Render(ID3D11DeviceContext* deviceContext, int indexCount, D3DXMATRIX worldMatrix,
	D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, ID3D11ShaderResourceView* texture,
	D3DXVECTOR3 lightDirection, D3DXVECTOR4 ambientColor, D3DXVECTOR4 diffuseColor,
	D3DXVECTOR3 cameraPosition, D3DXVECTOR4 specularColor, float specularPower)
{
	bool result;

	// Set the shader parameters that it will use for rendering.
	result = SetShaderParameters(deviceContext, worldMatrix, viewMatrix, projectionMatrix, texture,
		lightDirection, ambientColor, diffuseColor, cameraPosition, specularColor, specularPower);
	if (!result)
	{
		return false;
	}

	// Now render the prepared buffers with the shader.
	RenderShader(deviceContext, indexCount);

	return true;
}

bool LightShaderClass::InitializeShader(ID3D11Device* device, HWND hwnd, WCHAR* vsFilename, WCHAR* psFilename)
{
	HRESULT result;
	ID3D10Blob* errorMessage;
	ID3D10Blob* vertexShaderBuffer;
	ID3D10Blob* pixelShaderBuffer;

	D3D11_INPUT_ELEMENT_DESC polygonLayout[3];
	unsigned int numElements;
	D3D11_SAMPLER_DESC samplerDesc;
	D3D11_BUFFER_DESC matrixBufferDesc;
	D3D11_BUFFER_DESC cameraBufferDesc;
	D3D11_BUFFER_DESC lightBufferDesc;

	// Initialize the pointers this function will use to null.
	errorMessage = nullptr;
	vertexShaderBuffer = nullptr;
	pixelShaderBuffer = nullptr;

	// Compile the vertex shader code.
	result = D3DX11CompileFromFile(vsFilename, NULL, NULL, "LightVertexShader", "vs_4_0",
		D3D10_SHADER_ENABLE_STRICTNESS, 0, NULL, &vertexShaderBuffer, &errorMessage, NULL);
	if (FAILED(result))
	{
		// If the shader failed to compile it should have written something to the error message.
		if (errorMessage)
		{
			OutputShaderErrorMessage(errorMessage, hwnd, vsFilename);
		}
		// If there was nothing in the error message then it simply could not find the shader file itself.
		else
		{
			MessageBox(hwnd, vsFilename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

	// Compile the pixel shader code.
	result = D3DX11CompileFromFile(psFilename, NULL, NULL, "LightPixelShader", "ps_4_0",
		D3D10_SHADER_ENABLE_STRICTNESS, 0, NULL, &pixelShaderBuffer, &errorMessage, NULL);
	if (FAILED(result))
	{
		// If the shader failed to compile it should have written something to the error message.
		if (errorMessage)
		{
			OutputShaderErrorMessage(errorMessage, hwnd, psFilename);
		}
		// If there was nothing in the error message then it simply could not find the file itself.
		else
		{
			MessageBox(hwnd, psFilename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

	// Create the vertex shader from the buffer.
	result = device->CreateVertexShader(vertexShaderBuffer->GetBufferPointer(),
		vertexShaderBuffer->GetBufferSize(), NULL, &m_vertexShader);
	if (FAILED(result))
	{
		return false;
	}

	// Create the pixel shader from the buffer.
	result = device->CreatePixelShader(pixelShaderBuffer->GetBufferPointer(),
		pixelShaderBuffer->GetBufferSize(), NULL, &m_pixelShader);
	if (FAILED(result))
	{
		return false;
	}

	// Create the vertex input layout description.
	// This setup needs to match the VertexType structure in the ModelClass and in the shader.
	polygonLayout[0].SemanticName			= "POSITION";
	polygonLayout[0].SemanticIndex			= 0;
	polygonLayout[0].Format					= DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[0].InputSlot				= 0;
	polygonLayout[0].AlignedByteOffset		= 0;
	polygonLayout[0].InputSlotClass			= D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[0].InstanceDataStepRate	= 0;

	polygonLayout[1].SemanticName			= "TEXCOORD";
	polygonLayout[1].SemanticIndex			= 0;
	polygonLayout[1].Format					= DXGI_FORMAT_R32G32_FLOAT;
	polygonLayout[1].InputSlot				= 0;
	polygonLayout[1].AlignedByteOffset		= D3D11_APPEND_ALIGNED_ELEMENT;
	polygonLayout[1].InputSlotClass			= D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[1].InstanceDataStepRate	= 0;

	polygonLayout[2].SemanticName			= "NORMAL";
	polygonLayout[2].SemanticIndex			= 0;
	polygonLayout[2].Format					= DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[2].InputSlot				= 0;
	polygonLayout[2].AlignedByteOffset		= D3D11_APPEND_ALIGNED_ELEMENT;
	polygonLayout[2].InputSlotClass			= D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[2].InstanceDataStepRate	= 0;

	// Get a count of the elements in the layout.
	numElements = sizeof(polygonLayout) / sizeof(polygonLayout[0]);

	// Create the vertex input layout.
	result = device->CreateInputLayout(polygonLayout, numElements, vertexShaderBuffer->GetBufferPointer(),
		vertexShaderBuffer->GetBufferSize(), &m_layout);
	if (FAILED(result))
	{
		return false;
	}

	// Release the vertex shader buffer and pixel shader buffer since they are no longer needed.
	vertexShaderBuffer->Release();
	vertexShaderBuffer = nullptr;

	pixelShaderBuffer->Release();
	pixelShaderBuffer = nullptr;

	// Create a texture sampler state description.
	samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
	samplerDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
	samplerDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
	samplerDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
	samplerDesc.MipLODBias = 0.0f;
	samplerDesc.MaxAnisotropy = 1;
	samplerDesc.ComparisonFunc = D3D11_COMPARISON_ALWAYS;
	samplerDesc.BorderColor[0] = 0;
	samplerDesc.BorderColor[1] = 0;
	samplerDesc.BorderColor[2] = 0;
	samplerDesc.BorderColor[3] = 0;
	samplerDesc.MinLOD = 0;
	samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;

	// Create the texture sampler state.
	result = device->CreateSamplerState(&samplerDesc, &m_sampleState);
	if (FAILED(result))
	{
		return false;
	}

	// Setup the description of the dynamic matrix constant buffer that is in the vertex shader.
	matrixBufferDesc.Usage					= D3D11_USAGE_DYNAMIC;
	matrixBufferDesc.ByteWidth				= sizeof(MatrixBufferType);
	matrixBufferDesc.BindFlags				= D3D11_BIND_CONSTANT_BUFFER;
	matrixBufferDesc.CPUAccessFlags			= D3D11_CPU_ACCESS_WRITE;
	matrixBufferDesc.MiscFlags				= 0;
	matrixBufferDesc.StructureByteStride	= 0;

	// Create the constant buffer pointer so we can access the vertex shader constant buffer from within this class.
	result = device->CreateBuffer(&matrixBufferDesc, NULL, &m_matrixBuffer);
	if (FAILED(result))
	{
		return false;
	}

	// Setup the description of the camera dynamic constant buffer that is in the vertex shader.
	cameraBufferDesc.Usage = D3D11_USAGE_DYNAMIC;
	cameraBufferDesc.ByteWidth = sizeof(CameraBufferType);
	cameraBufferDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
	cameraBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
	cameraBufferDesc.MiscFlags = 0;
	cameraBufferDesc.StructureByteStride = 0;

	// Create the camera constant buffer pointer so we can access the vertex shader
	// constant buffer from within the class.
	result = device->CreateBuffer(&cameraBufferDesc, NULL, &m_cameraBuffer);
	if (FAILED(result))
	{
		return false;
	}

	// Setup the description of the light dynamic constant buffer that is in the pixel shader.
	// Note that ByteWidth always needs to be a multiple of 16 if using D3D11_BIND_CONSTANT_BUFFER or CreateBuffer will fail.
	lightBufferDesc.Usage = D3D11_USAGE_DYNAMIC;
	lightBufferDesc.ByteWidth = sizeof(LightBufferType);
	lightBufferDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
	lightBufferDesc.CPUAccessFlags = D3D10_CPU_ACCESS_WRITE;
	lightBufferDesc.MiscFlags = 0;
	lightBufferDesc.StructureByteStride = 0;

	// Create the constant buffer pointer so we can access the vertex shader constant buffer from within this class.
	result = device->CreateBuffer(&lightBufferDesc, NULL, &m_lightBuffer);
	if (FAILED(result))
	{
		return false;
	}

	return true;
}

void LightShaderClass::ShutdownShader()
{
	// Release the camera constant buffer.
	if (m_cameraBuffer)
	{
		m_cameraBuffer->Release();
		m_cameraBuffer = nullptr;
	}

	// Release the light constant buffer
	if (m_lightBuffer)
	{
		m_lightBuffer->Release();
		m_lightBuffer = nullptr;
	}

	// Release the matrix constant buffer.
	if (m_matrixBuffer)
	{
		m_matrixBuffer->Release();
		m_matrixBuffer = nullptr;
	}

	// Release the sampler state.
	if (m_sampleState)
	{
		m_sampleState->Release();
		m_sampleState = nullptr;
	}

	// Release the layout.
	if (m_layout)
	{
		m_layout->Release();
		m_layout = nullptr;
	}

	// Release the pixel shader.
	if (m_pixelShader)
	{
		m_pixelShader->Release();
		m_pixelShader = nullptr;
	}

	// Release the vertex shader.
	if (m_vertexShader)
	{
		m_vertexShader->Release();
		m_vertexShader = nullptr;
	}

	return;
}

void LightShaderClass::OutputShaderErrorMessage(ID3D10Blob* errorMessage, HWND hwnd, WCHAR* shaderFilename)
{
	char*			compileErrors;
	unsigned long	bufferSize, i;
	ofstream		fout;

	// Get a pointer to the error message text buffer.
	compileErrors = (char*)(errorMessage->GetBufferPointer());

	// Get the length of the message.
	bufferSize = errorMessage->GetBufferSize();

	// Open a file to write the error message to.
	fout.open("shader-error.txt");

	// Write out the error message.
	for(i=0; i<bufferSize; ++i)
	{
		fout << compileErrors[i];
	}

	// Close the file.
	fout.close();

	// Release the error message.
	errorMessage->Release();
	errorMessage = nullptr;

	// Pop a message up on the screen to notify the user to check the text file for compile errors.
	MessageBox(hwnd, L"Error compiling shader.  Check shader-error.txt for message.", shaderFilename, MB_OK);

	return;
}

bool LightShaderClass::SetShaderParameters(ID3D11DeviceContext* deviceContext, D3DXMATRIX worldMatrix,
	D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, ID3D11ShaderResourceView* texture,
	D3DXVECTOR3 lightDirection, D3DXVECTOR4 ambientColor, D3DXVECTOR4 diffuseColor,
	D3DXVECTOR3 cameraPosition, D3DXVECTOR4 specularColor, float specularPower)
{
	HRESULT result;
	D3D11_MAPPED_SUBRESOURCE mappedResource;
	unsigned int bufferNumber;
	MatrixBufferType* dataPtr;
	LightBufferType*  dataPtr2;
	CameraBufferType* dataPtr3;

	// Transpose the matrices to prepare them for the shader.
	D3DXMatrixTranspose(&worldMatrix, &worldMatrix);
	D3DXMatrixTranspose(&viewMatrix, &viewMatrix);
	D3DXMatrixTranspose(&projectionMatrix, &projectionMatrix);

	// Lock the constant buffer so it can be written to.
	result = deviceContext->Map(m_matrixBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
	if (FAILED(result))
	{
		return false;
	}

	// Get a pointer to the data in the constant buffer.
	dataPtr = (MatrixBufferType*)mappedResource.pData;

	// Copy the matrices into the constant buffer.
	dataPtr->world = worldMatrix;
	dataPtr->view  = viewMatrix;
	dataPtr->projection = projectionMatrix;

	// Unlock the constant buffer.
	deviceContext->Unmap(m_matrixBuffer, 0);

	// Set the position on the constant buffer in the vertex shader.
	bufferNumber = 0;

	// Now set the constant buffer in the vertex shader with the updated values.
	deviceContext->VSSetConstantBuffers(bufferNumber, 1, &m_matrixBuffer);

	// Lock the camera constant buffer so it can be written to.
	result = deviceContext->Map(m_cameraBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
	if (FAILED(result))
	{
		return false;
	}

	// Get a pointer to the data in the constant buffer.
	dataPtr3 = (CameraBufferType*)mappedResource.pData;

	// Get a pointer to the data in the constant buffer.
	dataPtr3->cameraPosition = cameraPosition;
	dataPtr3->padding = 0.0f;

	// Unlock the camera constant buffer.
	deviceContext->Unmap(m_cameraBuffer, 0);

	// Set the position of the camera constant buffer in the vertex shader.
	bufferNumber = 1;

	// Now set the camera constant buffer in the vertex shader with the updated values.
	deviceContext->VSSetConstantBuffers(bufferNumber, 1, &m_cameraBuffer);

	// Set the sahder texture resource in the pixel shader.
	deviceContext->PSSetShaderResources(0, 1, &texture);

	// Lock the light constant buffer so it can be written to.
	result = deviceContext->Map(m_lightBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
	if (FAILED(result))
	{
		return false;
	}

	// Get a pointer to the data in the constant buffer.
	dataPtr2 = (LightBufferType*)mappedResource.pData;

	// Copy the lighting variables into the constant buffer.
	dataPtr2->diffuseColor		= diffuseColor;
	dataPtr2->ambientColor		= ambientColor;
	dataPtr2->lightDirection	= lightDirection;
	dataPtr2->specularColor		= specularColor;
	dataPtr2->specularPower		= specularPower;

	// Unlock the constant buffer.
	deviceContext->Unmap(m_lightBuffer, 0);

	// Set the position of the light constant buffer in the pixel shader.
	bufferNumber = 0;

	// Finally, set the light constant buffer in the pixel shader with the updated values.
	deviceContext->PSSetConstantBuffers(bufferNumber, 1, &m_lightBuffer);

	return true;
}

void LightShaderClass::RenderShader(ID3D11DeviceContext* deviceContext, int indexCount)
{
	// Set the vertex input layout.
	deviceContext->IASetInputLayout(m_layout);

    // Set the vertex and pixel shaders that will be used to render this triangle.
    deviceContext->VSSetShader(m_vertexShader, NULL, 0);
    deviceContext->PSSetShader(m_pixelShader, NULL, 0);

	// Set the sampler state in the pixel shader.
	deviceContext->PSSetSamplers(0, 1, &m_sampleState);

	// Render the triangle.
	deviceContext->DrawIndexed(indexCount, 0, 0);
}